Catalytic conversion of 5-hydroxymethylfurfural (5-HMF) over Pd-Ru/FAU zeolite catalysts.

We present this study on FAU-type zeolites were prepared varying the Si/Al ratio (4, 5 and 6) and crystallization time (4, 6 and 8 h) to produce a highly pure and homogeneous material with enhanced surface area values. Bimetallic Pd-Ru and Pt-Ru (0.5 wt.% of each metal) were impregnated onto the zeolites matrix by the incipient wetness impregnation method. The materials were characterized by X-ray diffraction (XRD), nitrogen physisorption, Fourier Transform Infrared spectroscopy (FT-IR), Scattering Electronic Microscopy (SEM), Scattering and Transmission Microscopy (STEM), temperature-programmed desorption (TPD), temperature-programmed desorption (TPR) and Inductively Couples Plasma- Mass Spectrometer (ICP-MS). Results indicated that using lower Si/Al ratios favored the catalytic activity. Also, the longest crystallization time had a positive effect on surface area, homogeneous particle size distribution and crystallinity. The catalytic performance in the esterification of 5-hydroxymethylfurfural (5-HMF) to produce 5-acetoxymethylfurfural (AcMF) was investigated. The maximum 5-HMF conversion of 87.28 % was achieved using pure zeolite with relation Si/Al = 5, and 8 h of crystallization. Pd-Ru supported onto same zeolite showed a conversion of 84.22 %. The highest selectivity towards AcMF of 71.29 % with pure zeolite Si/Al = 5 and 8 h of crystallization was achieved, followed by Pd-Ru/FAU with Si/Al = 5 and 8 h of crystallization, achieving 60.42 %. Finally, results shown that the interaction between the properties of zeolitic support and the metallic species, specifically Pd, had a positive effect in the catalytic process the pristine zeolite showed improved catalytic characteristics related to its acid strength

Thermocatalytic degradation of lignin monomer coniferyl aldehyde by aluminum–boron oxide catalysts

Two aluminum–boron oxide catalysts were produced via a sol–gel method at pH 3 and 4 during the solution mixing step of the synthesis, these materials were employed in thermocatalytic degradation of coniferyl aldehyde (CA), which was used as a probe molecule of the lignin polymeric molecule and is comprised of the repetitive monomers coniferyl, sinapyl, and paracoumaryl. The two synthesized catalysts were mostly amorphous and mesoporous, aiding in permeability and percolation of CA. A commercial catalyst was compared (Pt/alumina at 1 wt%) with both catalysts synthesized in this work by kinetic tests by varying the CA concentration and inlet temperature. Under the same reaction conditions, the commercial catalyst showed higher activity than the aluminum–boron oxide catalysts, but the synthetic catalysts presented a wider variety of organic products than the commercial catalyst. In particular, two high-value products, isomers of eugenol and isoeugenol, were yielded in higher percentages. The experimental reaction rate data was fit to a Langmuir–Hinshelwood model, and kinetic parameters were analyzed, revealing how the adsorbed CA molecules on the catalytic surface had higher mobility with the synthesized catalyst compared with the commercial catalyst, the value of $\Delta S_{\mathrm{ads}}^{0}$ for the synthetic catalysts were $-$5.48 and $-$4.31 J/mol-K and for the commercial catalyst $-$37.17 J/mol-K

Thermocatalytic degradation of lignin monomer coniferyl aldehyde by aluminum–boron oxide catalysts

Two aluminum–boron oxide catalysts were produced via a sol–gel method at pH 3 and 4 during the solution mixing step of the synthesis, these materials were employed in thermocatalytic degradation of coniferyl aldehyde (CA), which was used as a probe molecule of the lignin polymeric molecule and is comprised of the repetitive monomers coniferyl, sinapyl, and paracoumaryl. The two synthesized catalysts were mostly amorphous and mesoporous, aiding in permeability and percolation of CA. A commercial catalyst was compared (Pt/alumina at 1 wt%) with both catalysts synthesized in this work by kinetic tests by varying the CA concentration and inlet temperature. Under the same reaction conditions, the commercial catalyst showed higher activity than the aluminum–boron oxide catalysts, but the synthetic catalysts presented a wider variety of organic products than the commercial catalyst. In particular, two high-value products, isomers of eugenol and isoeugenol, were yielded in higher percentages. The experimental reaction rate data was fit to a Langmuir–Hinshelwood model, and kinetic parameters were analyzed, revealing how the adsorbed CA molecules on the catalytic surface had higher mobility with the synthesized catalyst compared with the commercial catalyst, the value of $\Delta S_{\mathrm{ads}}^{0}$ for the synthetic catalysts were $-$5.48 and $-$4.31 J/mol-K and for the commercial catalyst $-$37.17 J/mol-K

Lithium recovery from Mexican geothermal brine via microwave-synthesized ion sieves

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Catalytic conversion of 5-hydroxymethylfurfural (5-HMF) over Pd-Ru/FAU zeolite catalysts

We present this study on FAU-type zeolites were prepared varying the Si/Al ratio (4, 5 and 6) and crystallization time (4, 6 and 8 h) to produce a highly pure and homogeneous material with enhanced surface area values. Bimetallic Pd-Ru and Pt-Ru (0.5 wt.% of each metal) were impregnated onto the zeolites matrix by the incipient wetness impregnation method. The materials were characterized by X-ray diffraction (XRD), nitrogen physisorption, Fourier Transform Infrared spectroscopy (FT-IR), Scattering Electronic Microscopy (SEM), Scattering and Transmission Microscopy (STEM), temperature-programmed desorption (TPD), temperature-programmed desorption (TPR) and Inductively Couples Plasma- Mass Spectrometer (ICP-MS). Results indicated that using lower Si/Al ratios favored the catalytic activity. Also, the longest crystallization time had a positive effect on surface area, homogeneous particle size distribution and crystallinity. The catalytic performance in the esterification of 5-hydroxymethylfurfural (5-HMF) to produce 5-acetoxymethylfurfural (AcMF) was investigated. The maximum 5-HMF conversion of 87.28 % was achieved using pure zeolite with relation Si/Al = 5, and 8 h of crystallization. Pd-Ru supported onto same zeolite showed a conversion of 84.22 %. The highest selectivity towards AcMF of 71.29 % with pure zeolite Si/Al = 5 and 8 h of crystallization was achieved, followed by Pd-Ru/FAU with Si/Al = 5 and 8 h of crystallization, achieving 60.42 %. Finally, results shown that the interaction between the properties of zeolitic support and the metallic species, specifically Pd, had a positive effect in the catalytic process the pristine zeolite showed improved catalytic characteristics related to its acid strength